Developers who want to start building B2G apps will want to check this out.

Mozilla is creating a new kind of mobile operating system that is aligned with standards-based Web technologies. The platform, called Firefox OS, consists of the Gecko HTML rendering engine, a thin hardware enablement layer built on the Linux kernel, and a user interface layer called Gaia that is implemented entirely in HTML and JavaScript.

The project was first announced in 2011 with the codename Boot2Gecko (B2G). It has matured considerably since then and is expected to arrive on handsets next year. Developers who want to get a head start will be pleased to learn that Mozilla has started producing daily builds of a B2G test environment that runs on conventional desktop computers.

These builds provide an x86-compatible B2G runtime for testing the Gaia shell and applications that are built for the platform. It’s a useful tool for Gaia contributors and for third-party developers who want to start building applications that are compatible with B2G. The builds are available for download from the Mozilla FTP server.

Users will have to do a little bit of configuration in order to run the software. The process involves obtaining the latest Gaia code from the GitHub repository and generating a profile to use in the environment. The steps to follow are documented on the Gaia Hacking page of the Mozilla Wiki. After I set up a profile, I was able to get the latest B2G nightly build running with Gaia on Mac OS X.

It’s important to note that the platform is still a work in progress and that the core application stack is under heavy development. What you see when you run the nightly isn’t really indicative yet of what the final user experience will be like. For more details, you can refer to a blog post that Mozilla’s Tony Chung published yesterday about the nightly builds.

It doesn't make sense to me why Mozilla is investing the time to create an open source, Linux-based mobile OS based on web technologies -- when WebOS is now open source, and accomplishes the exact same goals, and is a highly polished and well-established operating system that already has thousands of quality apps available.

WebOS has serious potential to compete directly with Android and iOS, and all it needs is a little love and acceptance from the open source community to become a heavyweight contender. (And OEM support, too, but Mozilla will have just as tough a battle to fight there as HP.)

I'm all for competition, don't get me wrong -- but success in the Mobile Platform arena is very tough, and Google and Apple are just too much muscle for the community to take on without a really focused effort. Further fragmentation in this market serves no purpose except to strengthen the two top contenders.

I just can't imagine what Mozilla intends to accomplish by fragmenting such a delicate space even further.

I don't think the WebOS API align very well with HTML5 related APIs, and that is why Mozilla is not adopting that. Never mind that WebOS is yet another Webkit based project, same as ChromeOS (and also the browsers built into Android and iOS). Webkit is rapidly replacing IE as the "built for" semi-standard engine, while Mozilla strives to be as true to the standard specs as they can be.

MeeGo/Jolla's (MeR+Nemo/Plasma etc) code-base is completely different to B2G's.I could see collaboration with OpenWebOS or Tizen though, in fact I'd love to see it.

webOS is centered around Webkit (just like iOS is). Not likely to happen without a lot of hacking done to it, and I can't imagine a lot of webOS-Internals folks interested in ice-skating uphill when Webkit already works.

Good point, forgot about that, still, stranger things do happen...Tizen's also centred around Webkit, so a tie-up of sorts w/OpenWebOS could be viable.(they've almost completely dropped EFL, & are almost exclusively HTML5 now)

Maybe I'm smoking something illegal here, but my pipe dream for an HTML/.js/CSS-driven UI would be the incredible amount of customization it should allow. I'd almost cream my pants for that level of control. THAT, to me, is the justification for this alternate OS to exist.